Florida veterinarians become first in U.S. to perform electric shock treatment

Borrowing from a Canadian veterinarian's unique expertise, University of Florida veterinarians recently became the first in the United States believed to have successfully performed intracardiac electrical conversion of a common arrhythmia in horses that causes irregular and fast heartbeats.

Two horses received the procedure in March 2005, including an Ocala thoroughbred named Captain who was part of a training exercise conducted for UF veterinarians by the individual who developed the technique, Canadian veterinarian Kim McGurrin, D.V.M. McGurrin developed the cutting-edge technique over the last four years along with her mentor, Peter Physick-Sheard, B.V.Sc., at the University of Guelph in Ontario, Canada.

Captain's arrhythmia had been treated medically several times but without success, said Mel Valley Farm owner-caretaker Carl Stump. Now, however, Captain appears to be doing well, Stump said.

"He is now training at a local place here in Ocala, so he is back to work," Stump said.

McGurrin said the intracardiac electrical conversion technique was developed to offer new treatment options for atrial fibrillation.

"It is excellent that UF is now capable of performing this procedure," McGurrin said. "We have applied this technique on more than 50 horses, including 44 client-owned horses referred from the states. Most horses have returned to performance and we now consider this procedure routine."

Amara Estrada, D.V.M., an assistant professor of veterinary cardiology at UF's College of Veterinary Medicine, and her colleague, Darcy Adin, D.V.M., were both involved in the recent UF procedure. Estrada said the cardiac abnormality for which the procedure is used is "an important arrhythmia for many reasons."

"Probably it is most important to horse owners and trainers of race horses because it causes poor performance and poor racing," Estrada said. "But certainly pet horses develop the condition as well."

It is also the most common arrhythmia in horses, occurring in 1 to 2 percent.

Estrada said irregular or fast heartbeat, also known as atrial fibrillation, causes a decrease in cardiac output, negatively impacting a horse's performance.

The disease is said to be frustrating to both horse owners and veterinarians because medical therapy frequently has to be administered many times and often has serious side effects.

"Typical medical treatment has consisted of antiarrythmic drugs given orally or intravenously, but the drugs can have fairly significant side effects, including toxicity," said Steeve Giguère, D.V.M., Ph.D., an associate professor of equine medicine at UF.

The UF veterinarians had heard of McGurrin and were aware that intracardiac electrical conversion technology was now being performed in horses at the University of Guelph routinely with "great success," Giguère said.

The procedure, which takes about two hours, involves surgically threading two catheters through veins in the horse's neck into the heart's right atrium and the pulmonary artery. Echocardiography is used to guide the placement of the catheters.

"Once the catheters are in the correct location, a short shock is delivered to 'reset' the atria and terminate the fibrillation, thus establishing a normal rhythm," Estrada said.

The equipment used to administer the shock is a biphasic defribrillator, the same technology used in human emergency medicine to treat cardiac arrhythmias.

"Most horses with atrial fibrillation do not have underlying heart disease," Giguère said. "So if you can restore their normal sinus rhythm, they usually return to their previous level of performance."